Osmolality and Carbohydrates - The Facts

We've seen a lot of hype lately about sports drinks and their osmolality as well as carbohydrates. I'm not going to go into great detail about this but I will make some basic points for your reference. If you would like to know more you can go to www.eload.net and look under "Science of e load(TM)". Be sure to take a look at the carbohydrate comparison chart to shed some better light on all the carb "hype" that's out there as well.

The Bottom Line
* In a 4-8% solution (40-80 grams/litre), dextrose, sucrose, maltodextrin and amylopectin are well tolerated. The longer chain carbohydrates like maltodextrin and amlyopectin may be associated with incomplete digestion, contributing to bloating, flatulence, diarrhea and dehydration.
* The higher the glycemic index, the faster the carbohydrate fueling, and the more advantageous to the athlete.
* Osmolality is not an important concept if the drink is a 4-8% solution (40-80 grams/litre). Indeed, from a gastrointestinal tolerance viewpoint, the more important concept may well be the total GRAMS of carbohydrate in solution, not the osmolality.
* Dextrose facilitates sodium absorption in the small intestine, and reabsorption from the kidneys, and because of this, is the carbohydrate of choice for a drink in the heat where sodium balance is crucial.
* Maltodextrin (and other long chain carbohydrates like amylopectin) cannot be used in higher percent solutions to increase caloric density, even though osmolality may remain lower than comparable dextrose based solutions. Higher percent solutions of long chain carbohyrates are known to slow gastric emptying and are thought to leave short chain carbohydrate remnants undigested. This can contribute to bloating, flatulence, diarrhea and dehydration.